1. Field of the Invention
The present invention relates to a pot aggregate for raising and transplanting seedlings, in which a number of pots to be formed with bottoms when expanded are aggregated, and a process for manufacturing the same.
2. Description of the Prior Art
Heretofore, there are known a variety of pot structures which are made of paper or paper-like thin film (as will be shortly called the "paper") so that they may be used as pots for raising and transplanting seedlings. Most of the pot aggregates have cylindrical structures having neither cover nor bottom. In U.S. Pat. No. 3,164,507 or B.P. No. 992,856, for example, there is disclosed a pot aggregate, in which a number of uncovered and unbottomed pots are aggregated by having their mutual side walls adhered by a water-soluble adhesive. In U.S. Pat. No. 4,132,337 or B.P. No. 1,559,343, on the other hand, there is disclosed a continuous pot aggregate, in which a series of individual pots can be extracted through perforations facilitating their tears.
The raising of seedlings and transplatations using the cylindrical pots of the prior art are accomplished by packing the expanded individual pots of the aggregate with soil, by sowing the seeds, by sprinkling water to raise the seedlings under raising conditions for a constant period, and by transplanting the seedlings separately one by one in the field by using a selected transplanter suitable for the seedlings.
If, in this case, the used pots have a relatively small sectional diameter, the soil packed in the pots is so sufficiently held that it will not drop. If the pot diameter exceeds 50 mm, the soil holding force of the pots becomes incomplete to allow the soil to drop.
The present invention relates to both a pot aggregate suited for preventing the soil from dropping out of the pots and a process for manufacturing the same.
The bottom pots made of the thin film are well known in the prior art. In Japanese Patent Publication No. 1126 of 1973 (as will be shortly referred to as Jap. 1126/73), for example, there is disclosed a seedling raising paper box aggregate, in which a number of unit boxes are formed by gluing and folding a long paper and are juxtaposed to one another with their outer walls overlapped and adhered by a water-soluble adhesive. In U.S. Pat. No. 4,021,966, on the other hand, there is disclosed the PLANTCUP ELEMENT, in which multiple unit cups each having a square section, four flat and parallel side walls and a bottom extended from the lower portions of only one pair of side walls (but not connected to the lower portions of the other pair of side walls) are arrayed in multiple parallel rows and in which the adjoining unit cups have their upper corners connected to each other. In U.S. Pat. No. 3,739,522, there are disclosed the HORTICULTURAL CELL SYSTEM, in which a sheet material such as a thermoplastic film is folded into two layers, in which these two layers are glued at a constant longitudinal interval to form a band and in which the adjoining bands are opened in an egg-shaped section to form cells, and a process for manufacturing the SYSTEM.
The seedling raising paper box aggregate disclosed in Jap. 1126/73 requires troublesome procedures for forming each of the unit boxes of the aggregate by gluing and folding one long sheet and for aggregating the unit boxes by overlapping and gluing the predetermined transverse widths of the flat folded boxes. If the unit boxes are thus individually formed, a major factor for dropping the production yield is raised for the mass production so that the aggregation is difficult to practice.
From the circumstances thus far described, it has been desired to complete the seedling raising bottomed pot aggregate which can be easily mass-produced.